Tape libraries have long been used in backup storage systems to store data. A tape library typically comprises one or more tapes and a mechanism, such as a tape drive, for reading and writing data on the tape(s). In addition, a backup software application manages the storage of data in the tape library. The backup software handles read and write requests received from client computers in a network and directs the requests to the tape library, for example.
Today, large amounts of data are stored in tape libraries. However, due to the inherent limitations of tape libraries, reading or writing data on a tape is often cumbersome and restrictive. Tape is a sequential medium; consequently it requires more time to access a desired data file stored on a tape than to access a file stored on a random-access medium such as a disk drive. In addition, many tape libraries comprise mechanical parts used to load tapes, etc., and sometimes require human intervention to identify a desired tape or perform other tasks. Therefore, in many cases, performing a data processing operation on data stored on tape is slower than performing the corresponding operation on a random access medium such as a disk drive. As a result, virtual tape libraries (“VTLs”), which typically use one or more disk drives to store data, are sometimes installed in backup storage systems to replace mechanical tape libraries.
When a VTL is added to a tape library system, read and write requests received after the installation of the VTL are typically directed by the backup software to the VTL for storage. Accordingly, any new data is stored in the VTL. Data stored in the VTL is sometimes stored using the same format used by the original, mechanical tape library. Adopting the same format allows a VTL to replace a mechanical tape library and continue to work with the existing backup software seamlessly, thereby avoiding costly changes to an enterprise's IT infrastructure.
When a backup system is updated to include a VTL, handling the existing data stored in the original tape library can pose a challenge. The format of data stored on tape(s) within a given tape library varies depending on the vendor of the tape library. In most cases, the format used in the original tape library does not match the format of the VTL that is added to the backup storage system. Known backup software applications cannot copy data stored in a tape library in a first format and store the data in a VTL in a second format.
Accordingly, in one common arrangement, the original tape drive is preserved in the backup storage system so that stored data may continue to be accessed, and a VTL is added and used for storing data in subsequent backup operations. The addition of a VTL can significantly improve the access speed of a backup storage system.
A separate challenge is posed by the large and growing amount of data stored in many existing VTLs. Because many backup storage systems store multiple copies of data files within a VTL to ensure redundancy, the organization of directory structures associated with the stored data can rapidly become cumbersome and inefficient. In such systems, the large amount and inefficient organization of the stored data can add to the time required to access a desired data file. Also subsequent backup operations may generate duplicate or redundant copies of data that has already been stored within the VTL, further exacerbating the problems associated with long term data storage.
Known backup systems are also not user-friendly. This sometimes becomes frustratingly evident to an ordinary user of an organization's computer network when a data file on the user's computer is lost or corrupted. In such cases, it may be necessary to restore the file from the backup storage system. To restore a data file, it is often necessary to direct a specified server, such as a media server, in the network to search for the location of the file in the backup system and to restore it. This procedure is usually beyond the capabilities of ordinary computer users, who are forced to seek out the assistance of the system administrator or to call the “Help Desk” in the organization's technical department. Sometimes multiple interactions between the user and the technical department are necessary. For example, after calling the Help Desk, a person from the technical department or the storage administrator may use the specified media server to search through the directories in the backup system, and find multiple versions of the requested file. The user may then be contacted and asked to specify which version is desired. This common procedure is inefficient at best, and can frequently be chaotic and frustrating for users.
In addition, in many organizations, only certain users of a computer network are granted “system administrator” rights (or similar authority), allowing such users authority to access all or a large part of the data stored anywhere within the network. Often, only a relatively small number of highly-trained individuals, such as those within the organization's information technology department are granted such rights. A user granted system administrator rights may access data stored in other user's computers, for example. Such users may also access archived data in a backup system, which may include tape drives, disk drives, or a combination of tape drives and disk drives. In such organizations, a large number of users do not have system administrator rights. Such users are typically allowed to store data and to access data already stored in their own computers, but are not allowed to access directly archived data stored in the backup storage system, or to store data directly in the backup storage system. These users must contact an individual with system administrator rights to access archived data or to store data in the backup storage system.